It is known in the art to equip a hinged or swinging door, or a sliding door with a door operator. As used herein, "operator" shall refer to a non-passive mechanism that produces some movement in a door. Thus, a motor coupled to produce door motion will be deemed an operator, whereas a door-closing coiled spring is not an operator. Further, as used herein, a device that opens a door but does not have integrated door-closing capability will be deemed a door opener.
Operator-equipped doors are frequently found in commercial establishments such as airports, malls or supermarkets where manual operation of the door may be inconvenient to users. Understandably, handicapped individuals, including bedridden and wheel-chair confined individuals, would greatly benefit from operator-equipped doors in their homes and businesses. Unfortunately, however, many factors make it unfeasible for such individuals to benefit from operator-equipped doors.
Many door operators are pneumatically, hydraulically, or electro-mechanically driven, and typically require substantial operating current and/or voltage. Installation of such an operator can include substantial modification to the door, the door frame, and indeed the structure wherein the door and door frame are mounted. Installation of such an operator frequently requires a building permit as well as the services of a skilled professional technician installer. As a result, "do-it-yourself" installation is generally precluded, especially by handicapped persons. The resultant cost of permits, equipment, and labor often prevents handicapped individuals from purchasing door operators for use at home and at work. In addition, conventional door operators often are expensive to maintain.
The installation of door operators is generally costly since different models are normally required depending upon whether the door is left-hinged or right-hinged, and/or whether the door swings inwardly or outwardly. This includes several different door operator linkage configurations which depend upon the operative placement thereof relative to the door. Hence, unless the operator technician first views the premises whereat installation is to occur, both the left-hinged and right-hinged models, as well as a variety of hardware, must be at hand to ensure that installation can be completed.
Moreover, the present door operators are generally large, bulky units which employ high torque, low rpm electric motors which require a minimal amount of gear reduction. This combination is utilized because the device must be capable of being back-driven manually when not powered. Motors of this type are typically large when compared to high rpm motors of equivalent horse power. Due to the large size of the magnets necessary to generate such a high torque at a low rpm, the motor and associated gear reduction mechanisms are relatively large. Often, these bulky door operators are too large to mount directly to the door and must be mounted on or above the door lintel. This may decrease the overall aesthetic appeal, and, without substantial structural modification, may preclude installation and operation of the unit altogether. For example, in a retrofit installation where the upper portion or edge of the door is at or very near the ceiling, the amount of space provided between the door lintel and the ceiling may be insufficient to mount the unit.
Operators utilizing smaller high rpm motors achieve some reduction in size but must increase the ratio of gear reduction to bring about appropriate opening and closing speeds. This has an unfortunate result of substantially increasing the force required to manually move the door when the operator is not powered. This high mechanical resistance precludes the utilization of a spring to bring about the closing of the door which must close under power. Thus, this type of operator must operate in the power mode at all times for all users due to the fact that the internal mechanisms are highly resistant to manual operation. A power outage can render a door thus equipped into a frozen state potentially trapping people in hazardous situations. Typically, operators utilizing door closure spring mechanisms, which are often internally mounted, use low revving high torque motors, and close doors with internal spring mechanisms. Such a spring is compressed during the opening cycle. During the closing cycle, the spring force must be sufficient to close the door, while counteracting the resistance forces caused by the motor and counter-rotating the series of gears (the gear train) coupled to the electric motor. However, this spring force must not be so large as to prevent or substantially impair manual operation of the door, especially for physically impaired individuals. These opposing limitations often result in poor closing performance in windy conditions.
Moreover, in an electrical outage, an individual attempting to further open or close the door may have to exert substantial manual force to overcome the resistance forces generated by the gear train, motor and/or internal or external door check spring. The magnitude of such resistance forces can exceed what a child, a frail or especially a handicapped person can exert. As a result, such individuals may be trapped within a room whose exit includes an operator-equipped door that is so frozen or inoperable to those individuals.
More recently, clutch mechanisms have been introduced between the motor assembly and the driving linkage assemblies. These mechanism are typically employed so as to cause slippage of the mechanisms when encountering obstructions in the powered opening and closing of the door. However, these arrangements most often act in conjunction with external or internal door closing springs for automatically closing the door. A typical example of these mechanisms may be found in U.S. Pat. No. 3,874,117 to Boehm which discloses a door opener (i.e., incapable of closing the door) that is to be used in combination with a standard hydraulic or mechanical door check for door closure. During its activity as a door opener the door is opened, and after passage has occurred, the clutch deactivates allowing a pre-existing spring mechanism to close the door.
This allows better closing characteristics than found in the previously described devices in which the drive-motor counter rotates during closing. Though Boehm's device was an improvement, it was cumbersome in that it required a separate mechanism to close the door. During a power outage, the Boehm system still presents an impediment to manual operation by individuals of limited physical capability because they must overcome the resistance caused by the mechanical doorcheck.
Prior art door operators further tend to preclude passive operation of the door. By passive operation it is meant that when not in the process of being moved by the door operator, the door should be manually movable by a user as though the door were not equipped with an operator or a spring-type closing mechanism. U.S. Pat. No. 5,018,304 to Langoria discloses an operator whose primary purpose is the moving of massive heavy radiation doors which are not readily movable by manual means. Langoria provides an emergency back-up power supply system so that egress may be maintained in the event of a power outage as manual use is extremely difficult. Langoria discloses the use of a clutch which has the purpose of selectively isolating the motor from the massive load. The slippage of the clutch accommodates this need. The clutch in Langoria's invention is engaged at all times either by line voltage or the back-up power supply system. It is never disengaged. The use of the clutch in Langoria is similar to that found in situations where the acceleration of large masses must be smoothly controlled. Examples of this can be found on industrial conveyor belts and on merry-go-rounds. In normal use Langoria's operator precludes manual operation of the door.
Many public buildings are required to have fire doors that are fully open normally but must close automatically in response to a fire alarm signal. This is most commonly achieved by the use of spring type door checks in conjunction with electromagnetic hold open devices which release with the loss of energizing current. After the fire alarm signal has ceased, these doors must again be fully opened. Reopening such doors is typically accomplished manually, a time consuming process if a great many doors are involved. Further, reopening such doors can require exerting a force sufficient to counter a spring bias used to close the doors. The magnitude of this force may in fact preclude non-muscular individuals and many handicapped individuals from being able to reopen the doors to escape a fire. In addition, fire doors that are operator-equipped can consume substantial electrical power in a hold open mode, and typically require an emergency standby power supply to maintain opening capability in the event of power interruption during a fire. In the absence of emergency standby power, even fire doors equipped with an operator can become a dangerous barrier to persons trapped within a room.
It is also known in the art to provide a door with an operator that may be remotely controlled by a user. Pressure sensing or light interrupt photodiode sensing mechanisms are commonly found in supermarket or airport doors, for example. U.S. Pat. No. 5,095,654 to applicant Eccleston discloses a radio controlled pneumatic door operator wherein depressing a single button on the remote control radio mechanism sequentially operates a deadbolt mechanism and door latch on the door and then causes the door to open. The door remains open until such time as the remote control button is again depressed, whereupon the process reverses. The disclosed mechanism could be attached without substantially modifying the door.
While the Eccleston mechanism was a boon to handicapped persons, it was basically a "go/no-go" control mechanism that, like other prior art door operators, did not readily permit a user to partially open or partially close a door.
In summary, what is needed is an inexpensive, low voltage powered door operator that can be installed by an untrained person without substantial modification to the door, door frame, or premises whereat it is used. To help minimize costs and make such operators readily available for purchase by handicapped persons, such an operator should function with various combinations of door configurations including a left-hinged or right-hinged door, and installation should not require expensive permitting procedures.
Further, to facilitate its use by handicapped and non-handicapped individuals, such a door operator should be remotely controllable, and should permit both active and passive use of the door, even in the event of a power interruption or another emergency.
Finally, such a door operator should also be operable in the same manner as a fire door closing device, and respond similarly in the interruption of operating electrical power. However, such a door operator should provide active operation capability to allow persons, including disabled persons, to exit a conflagration otherwise barred by a door.